Date: Mon, 10 Jan 1994 13:18:50 GMT From: taltar@beaufort.sfu.ca (Ted Altar) Subject: Martin Hulsey & Bowel Cancer Newsgroups: rec.food.veg Organization: Simon Fraser University, Burnaby, B.C., Canada The Willet et al. study [New Eng. J. of Med., 1990, 323(24):1664] is indeed worth reading directly for oneself. When it comes to any research supporting the vegetarian option, Dr. Hulsey simply can't be trusted to be impartial. Instead of noting that it was the animal fats that revealed the strongest relationship with bowel cancer, Dr Martin Hulsey would obscure the relationship by talking about percentage of fat by calories, as if it didn't matter what kinds of fats were being consumed. Obviously, it does matter, and this is a key finding of the Willet et al. study that Dr. Hulsey seems ignore or even attempt to obscure. Here are the actual results between animal vs non- animal fats: Animal Fats Relative Risk <39 g/day 1 39-47 1.22 48-55 1.27 56-64 1.55 >64 1.89 (p < .01) Vegetable Fats Relative Risk <10 1 10-13 1.04 14-17 .94 18-23 1.13 >23 .92 (p < .06) Clearly, the consumption of animal fats increases the risk for bowel cancer, but the consumption of vegetable fats doesn't. It is no wonder that Dr. Willett, the key author of the paper, would later say elsewhere: "If you step back and look at the data, the optimum amount of red meat you eat should be zero." Yet, Dr. Hulsey, who has a PhD in nutrition, would dogmatically assert: >These data are a direct refutation of those zealots >who would claim that "no meat is best." If logic here counts, then we would conclude from Dr. Hulsey's statement that Dr. Willett is a mere "zealot". Such name-calling is indeed offensive and unbecoming of somebody with a PhD in nutrition. Indeed, one always has to be suspicious of people who are so quick to call others "zealots", as maybe this in itself is the worst zealotry of all. Unfortunately, Dr. Hulsey just can't seem to be able to step back from his own anti-vegetarian prejudices and read for himself (and relevantly report for others on this vegetarian newsgroup) that: "We also examined specific foods in realtion to risk of colon cancer. Of the 61 foods included in the questionnaire, the strongest association was with BEEF, PORK, OR LAMB eaten as a main dish; woman who reported daily consumption had 2 and half times the risk of those who reported eating such meals less than once a month" (p. 1667) How much clearer can it be? And if we look at the consistent relationship between the consumption of red meats and colon cancer, clearly the less red meat consumed, the better. By extrapolation (and in light of other studies) none is best. Yet, here is the kind of moonshine that Dr. Hulsey wants us to believe: >Repeat after me, Ted: >CONSUMING SKINLESS CHICKEN SIGNIFICANTLY REDUCES THE RISK FOR >COLON CANCER; >NO INDIVIDUAL PLANT FOOD WAS FOUND TO PROVIDE SUCH BENEFIT! Now that I have been shouted at and exhorted to repeat Dr. Hulsey's self-comforting mantra, let us now return to the actual data, as opposed to what Dr. Hulsey would have us believe. Chicken and fish Relative Risk <22 1 22-28 .75 29-40 .99 41-64 .47 >64 .56 While we would hope that somebody with a PhD in nutrition would know better, it is maybe understandable why a layperson unfamilar with the reseach methodology/statistics might hastily conclude that eating chicken and fish reduces the risk for bowel cancer. Actually, it doesn't. First of all, note that unlike the key relationship of an increasing risk for colon cancer with each increase in the consumption of animal fats (see above), in this table on chicken and fish consumption we are dealing with a non-monotonic relationship (i.r., reduced risk is inconsistently related to increased consumption). Furthermore, what we have here is a relationship that is known to be confounded (i.e., correlated) with the reduction of eating red meat. That is, people who eat more chicken and fish ALSO eat less red meats (r = -21). Hey, it doesn't take a rocket scientist to figure that one out. Dr. Hulsey, of course, conveniently ignores to report for our benefit the clear warning by the authors that prefaced their reporting of the this apparent relationship between chicken/fish and colon cancer: "The association of specific foods with the risk of colon cancer may be difficult to intepret because of intercorrelations" Willett et al's warning is confirmed by inspecting the more important relationship of the RATIO of red meat to chicken & fish: Ratio of Red meat Relative Risk to chicken and fish <1.2 1 1.2 - 2.0 1.33 2.1 - 3.2 1.43 3.3 - 5.1 1.6 >5.1 2.49 In other words, what is again being revealed is the same relationship noted at the beginning, namely: the more red meat you eat, the greater the risk for colon cancer. The consumption of chicken & fish is merely reflecting that relationship since an increased consumption of chicken and fish is attended by an decrease in red meat consumption. It is that decrease in the consumption of red meat that makes for the lower risk. Notwithstanding Dr. Hulsey's false claims, you don't lower the risk for bowel cancer by eating chicken and fish, but by reducing the consumption of red meats. The less, the better, and by a warranted extrapolation, none is best. Hence, Willett's remark about the results (as quoted elsewhere): "If you step back and look at the data, the optimum amount of red meat you eat should be zero." I think Dr. Willett, who is the principle author and leading researcher of the study we are reviewing, should certainly know better than Dr. Hulsey who has proved himself to be rude and unable to be impartial. Regards, Ted